Senior high school students wearing Soviet-era navy uniform march during a daily ceremony of changing the guard of honor at the WW II Memorial to the Heroes of the defense of Sevastopol 1941-1942 in Sevastopol, Crimea, Saturday. Russia says it doesn't plant to invade mainland Ukraine. Olga Maltseva/AFP/Getty Images hide caption

itoggle caption Olga Maltseva/AFP/Getty Images

President Obama and other leaders met in The Hague. Clockwise from bottom left: European Union Council President Herman Van Rompuy, Canadian Prime Minister Stephen Harper, French President Francois Hollande, British Prime Minister David Cameron, Obama, German Chancellor Angela Merkel, Japanese Prime Minister Shinzo Abe, Italian Prime Minister Matteo Renzi and EU President Jose Manuel Barroso. Sean Gallup/Getty Images hide caption

itoggle caption Sean Gallup/Getty Images

Russian Foreign Minister Sergei Lavrov, left, and U.S. Secretary of State John Kerry before their talks Friday in London. Afterward, they reported no breakthroughs on finding a solution to the crisis in Ukraine. Brendan Smialowski/AP hide caption

itoggle caption Brendan Smialowski/AP

Armed men in unmarked military uniforms — who witnesses believe are Russian troops, but who Russian leaders say are "local self-defense" forces — stand outside the territory of a Ukrainian military unit in the Crimean village of Perevalnoye. Maxim Shipenkov /EPA/Landov hide caption

itoggle caption Maxim Shipenkov /EPA/Landov